The mandible consists of a horizontal, horse-shoe shaped portion having an upwardly and rearwardly extending posterior portion on each end. The upwardly and rearwardly extending posterior portions are called rami (ramus singular). The upper end of each ramus terminates in a forward coronoid process and a rearward condyloid process. The condyloid process consists of two portions—the condyle and its supporting structure, the neck. The condyle is a convex, knob-shaped protrusion that fits into a concave, cup-shaped socket in the temporal bone of the skull, called the glenoid fossa. The mandibular condyle and the glenoid fossa form the temporomandibular joint that allows the free movement of the lower jaw.
Disease or injury to the mandible may require resection of the condyloid process. After resection of the condyloid process, it is necessary to implant a prosthesis to span the missing segment of the mandible. When implanting a prosthetic condyloid process, it is important to provide a proper fit between the prosthetic condyle and the glenoid fossa. In other words, it is important to provide a proper condylar-head height on the ramus. Otherwise, the normal relationship between the condyle and glenoid fossa may be disturbed, resulting in disruption of the normal jaw function, or alteration of the occlusion or bite. Such a disruption may result in discomfort for the patient. Even in cases where it is only necessary to provide a temporary implant until a definitive reconstructive procedure can be performed, it is still important to provide a proper fit between the prosthetic condyle and the glenoid fossa to avoid unnecessary discomfort for the patient.